Hypergolic igniter



June 7, 1966 B. B. GOULD HYPERGOLIC IGNITER Original Filed March 8, 1961IN VEN TOR 5527 5. 601/40 BY I A TTOB/VEVS United States Patent3,254,603 HYPERGOLIC IGNITER Bert B. Gould, Berkeley, Calif., assignorto Ordtech Corporation, a corporation of California Continuation ofapplication Ser. No. 94,239, Mar. 8, 1961. This application Feb, 4,1965, Ser. No. 431,779 6 Claims. (Cl. 102-70) This invention relates toa method and apparatus for igniting miniature solid propellant rockets.

This application is a continuation of my copending application Ser. No.94,239, filed March 8, 1961, now abandoned and entitled HypergolicIgniter.

The ignition of large solid propellant rockets presents no particularproblems, but the ignition of miniature rockets involves seriousproblems. For one .thing, the physical sizes are so small thatconventional ignition systems cannot be scaled down sufliciently.Further, the burning time of miniature rockets is so short thatsubstantially uniform ignition must be obtained instantly throughout therocket in order to secure eflicient use of the propellant and to preventexcessive tail burning. The miniature rockets to which this inventionrelates are extremely small in size wherein the rocket has a diameter ofabout one-tenth inch, and a length of one and onehalf inches.Ordinarily, a central burning port of about 0.05 is employed with anozzle throat diameter of only 0.03". Thus, the ignition system must beextremely small and be adapted for insertion through a throat of only 30mils diameter.

In accordance with the present invention, it has been found that suchminiature rockets can be satisfactorily ignited employing a hypergolicfluid. Preferably the grain of the rocket is first coated with apyrotechnic mixture, it being understood, of course, that the hypergolicfluid which is selected is one which will ignite spontaneously with thepyrotechnic mixture, if used, or if not used, with the grain itself.Typical hypergolic combinations of a liquid or gas and a solid are redfuming nitric acid and phenylenediamine, hydrogen peroxide and redphosphorus, chlorine trifluoride and nitrocellulose.

A pyrotechnic mixture, such as black powder, Sb S and Ba (N09 boron andKNO or lead monoresorcinate and KClO may be mixed with nitrocellulose asa binder and used as a coating. Before drying, the surface may be dustedwith the solid component of the hypergolic combination. Alternatively,the solid component may be incorporated directly into the pyrotechnicmixture.

Various methods can be used for bringing the hypergolic fluid intocontact with the pyrotechnic material. Small tubes may be employed whichcan be inserted through the throat of the motor and which inject theliquid directly into the burning port. The tube need not enter the portdirectly but a spraying device can be employed to spray the fluidthrough the nozzle into the port. According to one embodiment of theinvention, the nozzle of the rocket is coated with a pyrotechnicmaterial, and the ignition of this coating induces ignition of thegrain. Further, the hypergolic liquid may be contained within the portitself in a suitable envelope or capsule and ignition effected merely byrupturing the capsule.

In the drawings forming part of this application:

FIGURE 1 is a sectional view of a rocket motor wherein liquid isinjected directly into the port;

FIGURE 2 is a sectional view of a rocket motor wherein a hypergolicliquid is sprayed externally of the port; and

FIGURE 3 is a sectional view of a rocket motor wherein the hypergolicliquid is contained within one or more capsules within the motor.

In all figures, 5 represents the casing of the motor, said casing havinga propellant grain 7 therein which is coated 3,254,603 Patented June 7,1966 with a pyrotechnic mixture 9. The motor is also provided with anozzle assembly 11.

In the embodiment of the invention shown in FIGURE 1 a source of ahypergolic liquid under pressure 13 is provided which is connected bymeans of the valve 15 to a manifold line 17 which terminates in a branchline 19. Since the rockets of the present invention are ordinarilypackaged in a cluster and fired in a salvo, ordinarily a plurality ofbranch lines 19 would be connected to the manifold line 17 although onlyone branch line is shown. Branch line 19 terminates well inside of theport 10 as at 21. In order to fire the rocket motors, it is onlynecessary to actuate the valve 15 releasing the hypergolic liquid intothe ports of the rockets.

In FIGURE 2 an embodiment of the invention is shown wherein a sprayhead23 or similar injection device is located some distance aft of one or aplurality of the rockets. The inner surface of the nozzle is coated witha pyrotechnic material 12 which extends into-the burning port 10 andconnects with the pyrotechnic material 9. Sprayhead 23 is connected to apressurized source of a hypergolic fluid, not illustrated. Here it isonly neces sary to release a cloud or spray 25 of the hypergolic fluidand the fluid ignites the mixture 12 which will propagate the flame tothe material 9 and thus ignite the rockets. In many instances it isunnecessary to coat the nozzle area since there will be suflicientpenetration of the fluid to ignite the rocket.

In FIGURE 3 an alternate form is shown wherein a hypergolic fluid iscontained within a frangible capsule- 27. In order to fire the rocket,it is only necessary to insert a needle-like object 29 through thethroat of the rocket and rupture the capsule 27. This can be done eitherby moving the motor backwards over a fixed mandrel or by holding themotor still and inserting the mandrel into the cavity.

It is obvious that any liquid, vapor and aerosols of solid or liquidsmay be employed providing they are hypergolic with the pyrotechnicand/or propellant compositions employed.

I claim:

1. An igniter for a miniature solid propellant rocket. comprising incombination:

(a) a solid propellant rocket having a discharge nozzle and a solidpropellant grain with a central burning port;

(b) a source of a hypergolic fluid external of said discharge nozzle;

(c) a coating of a pyrotechnic mixture on the walls of said burningport, said mixture being hypergolically sensitive with said fluid; and

(d) means for injecting said fluid from said source onto said coating.

2. The device of claim 1 which includes a small tube in the port of therocket through which the hypergolic fluid is injected into the port.

3. The device of claim 1 wherein the inside surface of the rocket nozzleis coated with a pyrotechnic material.

4. The device of claim 1 which includes a frangible container within theport of the rocket containing the hypergolic fluid and means for ruptureof said frangible container.

5. An igniter for a miniature solid propellant rocket comprising incombination:

(a) a solid propellant rocket having a discharge nozzle and a solidpropellant grain with a central burning port in alignment with saiddischarge nozzle;

(b) a separate source of hypergolic fluid;

(c) a coating on the walls of said burning port formed of a solidpyrotechnic mixture which is hypergolically sensitive with said fluid;

3 (d) means for release of hypergolic fluid from said source forengagement with said coating; and (e) a coating of a pyrotechnicmaterial as a coating on the rocket nozzle. 6. A device as claimed inclaim 5 in which the hypergolic fluid is introduced into engagement withthe coating of pyrotechnic material on the rocket nozzle.

4 References Cited by the Examiner UNITED STATES PATENTS 2,959,00111/1960 Porter 1027O 2,974,484 3/196-1 Cooley 102-865 BENJAMIN A.BORCHELT, Primary Examiner. G. H. GLANZMAN, Assistant Emminer.

1. AN IGNITER FOR A MINIATURE SOLID PROPELLANT ROCKET COMPRISING INCOMBINATION: (A) A SOLID PROPELLANT ROCKET HAVING A DISCHARGE NOZZLE ANDA SOLID PROPELLANT GRAIN WITH A CENTRAL BURNING PORT; (B) A SOURCE OF AHYPERGOLIC FLUID EXTERNAL OF SAID DISCHARGE NOZZLE; (C) A COATING OFPYROTECHNIC MIXTURE ON THE WALLS OF SAID BURNING PORT, SAID MIXTUREBEING HYPERGOLICALLY SENSITIVE WITH SAID FLUID; AND (D) MEANS FORINJECTING SAID FLUID FROM SAID SOURCE ONTO SAID COATING.